Tech Stuff - Network Tones

The following audible (call progress) tones and power levels are used in North America (full definition see ANSI T1.401 Appendix D 1988).

Name

Frequency (Hz)

Pattern

Dial tone

350 + 440

Steady on

Message Waiting

350 + 440

10 bursts (0.1sec on, 0.1 sec off) then
steady on

Recall dial tone/
Confirmation tone

350 + 440

3 bursts (0.1 sec on, 0.1 sec off) then
steady on

Line busy

480 + 620

0.5 sec on, 0.5 sec off, repeating

Reorder

480 + 620

0.25 sec on, 0.25 sec off, repeating

Audible Ringing

440 + 480

2 sec on, 4 set off, repeating

Power Levels

Name

350 Hz

440 Hz

480 Hz

620 Hz

Dial tone
Message Waiting
Recall

-29 to -10 dBm

-29 to -10 dBm

Line Busy
Reorder

-52 to -21 dBm

-52 to -21 dBm

Ringing

-47 to -16 dBm

-47 to -16 dBm

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